The core will provide uniform, careful oversight of the animals, their diets and all the procedures for handling them and their tissues. It will provide and keep current the central repository of data related to the animals. It will provide the primary data on body weight, feed intake (where measured), development of palpable tumors, gross findings at necropsy on all animals in all projects and the histopathologic and immunohistochemical findings on the rats. Dr. Rogers will work with Dr. Cardiff to reconcile histopathologic results in the mice and rats. The core will provide uniform tissue samples and fractions to investigators for their biochemical and molecular studies. These functions will assure comparability of the animal tissues used in the three component projects and permit direct comparisons of the results of a wide variety of studies on the same tissues. These procedures promote efficient use of tissues and animals, reducing overall numbers of animals needed. Drs. Sonenshein, Sherr, and Rogers have worked closely over the past four years in a similarly-designed program and found it to be highly productive and efficient.